Venture GlareGuard High Bay Metal Halide

The special lamp pictured here was marketed for a brief period by the American manufacturer Venture Lighting. It was sold under the "Glare Guard" trade name and was originally developed in 1986 together with luminaire firm Qualite, to reduce troublesome spill light in sports lighting installations. Thereafter it was promoted to reduce the glare present in ordinary high bay industrial lighting installations.

The novel feature of this lamp is an internal aluminised reflector on the bulb crown. The size of the aluminised region is chosen such that from ground level, it is not possible to view the arc tube, which normally leads to high glare levels. Furthermore the aluminium layer acts as a secondary reflector which works well with most high bay luminaires. In normal situations, stray light from the arc tube is free to leave the luminaire at any angle and some of the light leaving the arc tube is not controlled by the external reflector at all. With the GlareGuard lamp this stray light is reflected back on to the main external reflector which redirects it into the main beam.

Consequently the beam angle from each luminaire is reduced and it has a sharper cut-off at the edge. At no point from the ground can the arc tube be directly viewed, so glare is considerably reduced. The lamp was marketed primarily to factories where highly detailed work was being carried out to reduce eye strain and fatigue. It is a very sensible innovation indeed and certainly does improve the design of many installations. But presumably owing to the high price and availability from only one manufacturer, it never became popular enough to justify continued production, and it was made obsolete in 1997.